RU2419032C2 - Device for modification of gaseous fuel composition - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: device consists of facilities for gaseous fuel supply, of facilities for supply of oxidant, and of fuel combustion facilities utilising oxidant for partial combustion of first part of fuel with products of partial combustion including intermediate combustion products. Also, products of partial combustion are mixed with the rest part of fuel, partially not combusted, thus facilitating production of modified fuel. Partial combustion is controlled to ensure output of intermediate combustion products required for production of preliminary specified modified fuel.

EFFECT: increased stability of combustion process.

23 cl, 10 dwg

Description

The present invention relates to a device for modifying the composition of gaseous fuels.

It is known that to reduce the content of undesirable by-products of the combustion process in gas turbine engines, the combustion temperature is reduced, i.e. reduce emissions from the engine of pollutants. A decrease in the combustion temperature reduces the formation of NOx (nitrogen oxides). However, the decrease in this temperature should not be too significant, because otherwise it will lead to an increase in the content of carbon monoxide and unburned hydrocarbons.

The problem that occurs when lowering the combustion temperature in a gas turbine engine is the weakening of the combustion flame or in the failure of the flame. In other words, a decrease in the combustion temperature often leads to unstable combustion. If the combustible mixture of fuel with air contains fuel rich in inclusions, then these inclusions really help maintain the combustion process at lower temperatures. However, the level of emission of pollutants will not be as low as it could be if at a lower temperature the combustible mixture was a perfect and homogeneous mixture.

As you know, this problem when using gaseous fuel in gas turbine engines is solved by mixing or enriching the fuel with hydrogen. Hydrogen has a very high speed of propagation of the combustion flame and, therefore, helps to maintain the combustion flame. The hydrogen used can be isolated from the fuel itself by chemical conversion of the fuel. Alternatively, the hydrogen contained in the cylinders may be used. The production of hydrogen from fuel is a complex and accordingly expensive process. In the case of balloon hydrogen, a large number of cylinders may be required under operating conditions with a limited available volume.

In accordance with a first aspect of the present invention, there is provided a device for modifying a gaseous fuel composition comprising means for supplying gaseous fuel, means for supplying an oxidizing agent, means for burning fuel using an oxidizing agent to partially burn a first portion of the fuel to produce partial combustion products, including intermediate combustion products while the products of partial combustion are mixed with the rest of the fuel, not partially burned, thereby providing teachings modified fuel, wherein the partial combustion is controlled so as to ensure the preparation of intermediate combustion products required to produce a predetermined modified fuel.

Preferably, the fuel supply means include a conduit through which gaseous fuel flows; oxidizing agent means include one or more inlet pipes that pass through the walls of said conduit; and means for burning fuel are located essentially inside the pipeline in the path of movement of the fuel flow through the pipeline.

Preferably, the combustion means includes a burner for mixing the oxidizing agent with the first part of the fuel, a combustion chamber located downstream of the burner, in which (in the chamber) said partial burning of the first part of the fuel is carried out, and an ignitor for initiating partial combustion of the fuel.

The combustion chamber, in its zone downstream, may contain holes to reduce combustion, while the rest of the fuel, not partially burned, passes through these holes to reduce combustion from an external volume (outside) to the internal volume of the combustion chamber with so as to weaken the process of partial combustion of fuel in the chamber and mix with the specified products of partial combustion.

The combustion chamber may include openings for effusion cooling, through which the indicated remaining part of the fuel, not partially burned, passes from the external volume into the internal volume of the combustion chamber to cool the chamber walls.

In the device described below as an example of execution, the burner comprises an upstream disc element provided with openings for the passage of an oxidizer in communication with said inlet feed pipes, a radial swirler installed downstream of said disc element, intended to give such direction to said the first part of the fuel, so that it is transported essentially radially inward and acquires a rotational vortex movement, while in the radial swirl the oxidizer stream falls from the holes in the disk element to mix it with the first part of the fuel, and a prechamber is placed downstream of the radial swirler, into which the vortex flow of fuel and oxidizer from the swirler enters.

In the apparatus described below by way of example, the upstream disk element is configured such that fuel can pass around and through the central part of the disk element, while the fuel flow hits the central part and cools it before it passes around / through the central part disk element and reaches the central zone of the radial swirl.

The device described below as one exemplary embodiment is provided with a shielding extension of said combustion chamber, which facilitates mixing said remaining part of the fuel, not partially burned, with partial combustion products, while the shielding extension is separated by a gap from the pipe walls so that it can be cooled by fuel passing between this extension cord and the walls of the pipeline.

The device described below as an example includes a vortex diode located upstream of the combustion means, which serves to reduce the cross section upstream of the pressure pulsations and / or noise arising from the combustion during operation of the combustion means.

Preferably, said partial combustion control comprises controlling the ratio of oxidizer to partial combustion fuel to facilitate the production of an intermediate combustion product, carbon monoxide. The gaseous fuel may be methane.

The present invention extends to a gas turbine engine equipped with the above-described device installed in the fuel supply line.

In accordance with a second aspect of the present invention, there is provided a method of modifying the composition of a gaseous fuel, comprising the steps of: using an oxidizing agent to partially burn the first portion of the gaseous fuel to produce partial combustion products including intermediate combustion products, and mixing the partial combustion products with the rest of the partially combustible fuel thereby providing a modified fuel, wherein said partial combustion is controlled so that careless preparation of intermediate combustion products required to produce a predetermined modified fuel.

The invention will now be disclosed by way of example with reference to the accompanying drawings.

1 is a schematic illustration of a first device according to the present invention.

Figure 2 is a view in the direction shown by arrow B in figure 1.

Figure 3 is a view in the direction shown by arrow A in figure 1.

Figure 4 is a section along the line IV-IV in figure 1.

5 is a schematic illustration of a second device according to the present invention.

6 is a section along the line VI-VI in figure 5.

7 is a schematic illustration of a third device according to the present invention.

Fig. 8 is a schematic illustration of a fourth device according to the present invention.

9a, 9b and 9c are diagrams illustrating the production of carbon monoxide using a device of the present invention.

FIG. 10 is a table showing a typical exploded composition of gaseous fuels for gas turbine engines.

The device described below enriches the supplied gaseous fuel for a gas turbine engine, including methane, with products of partial combustion of a part of this supplied fuel, including intermediate combustion products, in particular carbon monoxide. The high propagation speed of the carbon monoxide flame contributes to the maintenance of the combustion flame during subsequent combustion of enriched fuel in a gas turbine engine. In addition, carbon monoxide is particularly suitable for maintaining a flame at the interface between high and low flow rates, i.e. carbon monoxide is characterized by high resistance to disturbances. This property is desirable to prevent flame failure during combustion in a gas turbine engine.

The first device, shown in figures 1-4, contains means 2 for supplying fuel, for example a pipeline for supplying fuel under high pressure, including methane, means (3) for supplying an oxidizing agent, for example supply pipes for air inlet, means for burning, for example a burner 1, the flame tube 10 and the igniter 9. The inlet pipes are a mechanical support for the burner 1. Separate support struts can be used as an alternative. Fuel, including methane, flows through the fuel supply pipe in the direction shown by arrow 14 to supply fuel to the gas turbine engine. The burner 1 includes a front disk element 6, a radial swirler 5 containing swirl channels 5a (see figure 4), and the chamber 7.

Fuel, including methane, flows from the left side in FIG. 1 and passes between the supply pipes for air inlet. Some of the fuel enters the swirl channels 5a, during the passage of which it moves radially inward in the direction of the prechamber 7. The rest of the fuel continues to flow through the fuel supply pipe and reaches the flame tube 10.

Air is supplied through the supply pipes and injected through the openings 4 located in the rear surface of the disk element 6. Fuel and air are mixed in a swirling flow inside the pre-chamber 7 in such a way that a combustible mixture is formed in the central region of the stream away from the walls of the pre-chamber 7.

The resulting combustible mixture enters the flame tube 10. The igniter 9 initiates the initial combustion (flame is shown in figure 1 at 8). After this, combustion takes place in a self-sustaining mode. The formation of a combustible mixture in the central zone of the pre-chamber 7 at a distance from the walls of the pre-chamber 7 ensures that the hot gases, due to the flame 8, do not come into contact with the walls of the flame tube 10 and therefore do not damage them by heat. In addition, holes 11 for effusion cooling are made in the walls of the flame tube 10, allowing a certain amount of the aforementioned remaining part of the fuel (non-combustible part of the fuel) to pass through the pipe 10 (see arrows 21) in order to remove the heat radiated by the flame 8 to the pipe 10.

The air supply through the supply pipes is organized in such a way that it is sufficient for complete combustion of the fuel with which this air is mixed in the pre-chamber 7. In other words, the air supply is provided such that the mixture of air with fuel in the pre-chamber 7 is a fuel rich in such degrees, so that only partial combustion of the fuel takes place inside the flame tube 10. This partial combustion results in intermediate combustion products, in particular carbon monoxide. Inadequate air supply, in addition, leads to the fact that combustion inside the pipeline for supplying fuel does not become an uncontrolled process.

The combustion inside the flame tube 10 is attenuated by dilution jets 12 formed by part of the non-combustible fuel passing through the extinguishing holes 13 present in the flame tube 10. The dilution jet supply also helps to thoroughly mix unburned fuel with partial combustion products including carbon monoxide . The attenuation of combustion by means of jets 12 for dilution minimizes the production of undesirable intermediate products of combustion, namely carbon and soot (carbon formation occurs over a longer period of time compared with carbon monoxide). Mixing the hot partial combustion products with non-combustible fuel cools the combustion products, preventing them from heating up too much.

The resulting fuel, containing methane and enriched in carbon monoxide, is then fed to a gas turbine engine. As explained above, carbon monoxide creates the effect of stabilizing the combustion process in a gas turbine engine. The goal is that the air / fuel mixture partially burnt in the flame tube 10 is such as to produce the maximum amount of carbon monoxide.

9a, 9b, and 9c are diagrams illustrating the formation of carbon monoxide (in mole fractions) for various equivalent ratios (EO) of mixture components and pressures. The diagram in Fig. 9a is constructed for the temperature of the fuel, including methane 300K (149 ° C); the diagram in Fig. 9b is for a fuel temperature of 400K (204 ° C), and the diagram in Fig. 9c is for a fuel temperature of 500K (260 ° C). The equivalent ratio of the contents of the components of the air / fuel mixture (EO) is defined as the ratio of fuel to air in the mixture, divided by the so-called stoichiometric value. The indicated stoichiometric value is the fuel / air ratio that provides complete combustion (as opposed to partial combustion). Thus, a mixture rich in fuel is characterized by a value of EO greater than unity. The pressure in the diagrams refers to the pressure of the fuel, including methane, in the fuel supply pipe.

As can be seen, the mixture of air and fuel with an EO value of approximately 2 to 3.5 tends to maximize the production of carbon monoxide in the temperature range from 149 to 260 ° C.

The second embodiment of the device shown in FIGS. 5 and 6 is the same as the first, except that the circular central part 16 of the front disk element 6 of the burner 1 is made with a somewhat reduced thickness and an annular gap formed around it 23. The central part 16 is held inside the disk element 6 by means of support links 31 (see Fig.6). Fuel 15 hits the front surface of the central part 16 and cools it before it passes through the annular gap 23 and is mixed with air in the pre-chamber 7. As an alternative to the annular gap surrounding the central part 16, through holes. In this case, the fuel before it passes through these holes and mixes with air in the pre-chamber 7, will hit the front surface of the Central part 16 and cool it.

7 shows a third embodiment of the device, which is the same as the first, except that the flame tube 10 is supplemented by a shielding extension 17 as a continuation thereof. The shielding extension 17 is of sufficient length to allow full mixing with the jets 12 for dilution of non-combustible fuel with partial combustion products obtained in the flame tube 10. The presence of a shielding extension 17 ensures that the "hot spots" of the partial combustion products do not reach the walls of the pipeline, which m It would loosen the walls, contribute to their corrosion and burn through.

On Fig presents the fourth embodiment of the device, which is made the same as the third, except that upstream of the burner 1 is additionally mounted a vortex diode 18 in order to significantly reduce the passage section of the channel upstream from the place of pressure pulsations and / or noise arising from combustion produced by the device, for example, in order to avoid the propagation of disturbances from the same device connected to the same fuel manifold 19.

In the apparatus described above by way of example, a radial swirler mixes a portion of the gaseous fuel supply with air so as to create a fuel rich mixture for partial combustion. It should be borne in mind that there is no need to carry out this mixing using a radial swirler. For example, mixing can be carried out using an axial swirler or using a mixing device other than the swirler.

The apparatus described above by way of example enriches carbon monoxide with pure methane used as fuel for a gas turbine engine. Of course, in the practical commercial use of the device, the enriched fuel of a gas turbine engine cannot be pure methane, but industrial fuel of a gas turbine engine can be used. The following are examples of three industrial fuels for a gas turbine engine: biogas, UK natural gas and refinery gas. In the table of FIG. 10 shows typical component compositions of these three fuels. The amounts in the table are given in volume percent.

In the apparatus described above by way of example, a portion of the gaseous fuel is withdrawn, partially burnt, and then mixed with the rest, not partially burnt, to produce the final fuel. Partial combustion is controlled so as to enhance the production of an intermediate combustion product, carbon monoxide, so that the final fuel is enriched in carbon monoxide, which improves the stability of the combustion process. However, it is necessary to take into account that partial combustion of the fuel can be regulated in order to activate the process of obtaining an intermediate product of combustion other than carbon monoxide, which also provides increased stability of combustion. It should be understood that the task of partial combustion is to provide intermediate combustion products in which the disposable chemical valence bonds are not completely saturated. Such products are characterized by high chemical activity (reactivity) and, therefore, have a high flame propagation speed and resistance to disturbances (see the mention of this earlier with respect to carbon monoxide). In addition, such products are also able to weaken or "capture" the bonds of unburned fuel molecules, increasing the chemical activity of these molecules. In addition, it should be noted that the final enriched fuel due to partial combustion is at an elevated temperature. This elevated temperature also increases the reactivity of the fuel.

It should also be understood that the present invention creates the desired effect of reducing a certain amount of bound nitrogen present in the fuel composition by reducing bound nitrogen to nitrogen N ₂ . Although gaseous fuels usually contain a very small amount of bound nitrogen, the recovery of a certain amount of nitrogen bound in the fuel is useful when trying to obtain an ultra-low or extremely low yield of pollutants from the fuel.

The device described above by way of example enriches gaseous fuel intended for supply to a gas turbine engine. It should be appreciated that the present invention can be used to enrich gaseous fuels and to feed a reciprocating internal combustion engine in which it is desired or desirable to increase the rate of combustion of fuel in the engine.

Claims (23)

1. A device for modifying the composition of gaseous fuels, containing means (2) for supplying fuel, means (3) for supplying an oxidizing agent, means (1, 9, 10) for burning fuel, using an oxidizing agent for partial burning of the first part of the fuel to produce products partial combustion, including intermediate combustion products, while the partial combustion products are mixed with the rest of the fuel, not partially burned, thereby providing a modified fuel, while the means (10) for burning sleep fuel it is provided with openings (13) for attenuating combustion, providing additional control of partial combustion using jets (12) for dilution formed from the rest of the fuel, the rest of the fuel entering the partial combustion zone in order to provide intermediate combustion products necessary for obtaining a predefined modified fuel. 2. The device according to claim 1, in which the means (2) for supplying fuel include a pipeline through which gaseous fuel flows, the means (3) for supplying an oxidizing agent include one or more supply pipes that pass through the walls of said pipeline, and the means ( 1, 9, 10) for burning fuel, located essentially inside the pipeline on the path of movement of the fuel flow through the pipeline. 3. The device according to claim 2, in which the means (1, 9, 10) for burning fuel include a burner for mixing the oxidizing agent with the first part of the fuel, a combustion chamber located downstream of the burner, in which said partial burning of the first parts of the fuel, and an ignitor to initiate partial combustion of the fuel. 4. The device according to claim 3, in which in the area located downstream of the combustion chamber (10), openings (13) are made to reduce combustion. 5. The device according to claim 3, in which the combustion chamber is provided with holes (11) for effusion cooling, through which the indicated remaining part of the fuel, not partially burned, passes from the external volume into the internal volume of the combustion chamber to cool the chamber walls. 6. The device according to claim 4, in which the combustion chamber is provided with holes (11) for effusion cooling, through which the indicated remaining part of the fuel, not partially burned, passes from the external volume into the internal volume of the combustion chamber to cool the walls of the combustion chamber. 7. The device according to claim 3, in which the burner contains a disk element (6) located upstream, provided with openings (4) for the passage of the oxidizer, which are in communication with the specified input supply pipes, a radial swirler (5), located downstream of the specified disk element (6), designed to give the specified first part of the fuel in such a direction that it is transported essentially radially inward and acquires a vortex movement, while the flow of oxidant from the hole enters the radial swirler (5) sty (4) in the disc member (6) for mixing it with the first portion of fuel, and downstream of the radial swirler (5) is arranged pre-chamber (7) that receives the swirling flow of fuel and oxidant from the swirler (5). 8. The device according to claim 4, in which the burner contains a disk element (6) located upstream, provided with openings (4) for the passage of the oxidizer, which are in communication with the specified input supply pipes, a radial swirler (5), located downstream of the specified disk element (6), designed to give the specified first part of the fuel in such a direction that it is transported essentially radially inward and acquires a vortex movement, while the flow of oxidant from the hole enters the radial swirler (5) sty (4) in the disc member (6) for mixing it with the first portion of fuel, and downstream of the radial swirler (5) is arranged pre-chamber (7) that receives the swirling flow of fuel and oxidant from the swirler (5). 9. The device according to claim 5, in which the burner contains a disk element (6) located upstream, provided with openings (4) for the passage of the oxidizer, which are in communication with the specified input supply pipes, a radial swirler (5), located downstream of the specified disk element (6), designed to give the specified first part of the fuel in such a direction that it is transported essentially radially inward and acquires a vortex movement, while the flow of oxidant from the hole enters the radial swirler (5) sty (4) in the disc member (6) for mixing it with the first portion of fuel, and downstream of the radial swirler (5) is arranged pre-chamber (7) that receives the swirling flow of fuel and oxidant from the swirler (5). 10. The device according to claim 6, in which the upstream disk element (6) is made such that fuel can pass around and through the central part (16) of the disk element (6), while the fuel flow hits the central part (16 ) and cools it before it passes around / through the central part (16) of the disk element and reaches the central zone of the radial swirler (5). 11. The device according to any one of claims 4 to 10, further comprising a shielding extension (17) of said combustion chamber that facilitates mixing said remaining fuel, not partially burned, with partial combustion products, while the shielding extension (17) is separated by a gap from the walls of the pipeline so that it can be cooled by fuel passing between this shielding extension (17) and the walls of the pipeline. 12. The device according to any one of claims 2 to 10, further comprising a vortex diode (18) located upstream of the means (1, 9, 10) for combustion, which serves to reduce the flow cross section upstream of the place of pressure pulsations and / or noise arising during combustion during the operation of means (1, 9, 10) for combustion. 13. The device according to claim 11, in addition, containing a vortex diode (18) located upstream of the means (1, 9, 10) for combustion, which serves to reduce the cross section upstream from the place of pressure and / or noise pulsations arising in the combustion process during the operation of means (1, 9, 10) of combustion. 14. The device according to any one of claims 1 to 10, in which the regulation of partial combustion includes regulating the ratio of the contents of the oxidizing agent and fuel, carried out by partial combustion, contributing to the production of an intermediate combustion product - carbon monoxide. 15. The device according to claim 11, in which the regulation of partial combustion includes regulating the ratio of the contents of the oxidizing agent and fuel, carried out during partial combustion, contributing to the production of an intermediate product of combustion - carbon monoxide. 16. The device according to 12, in which the regulation of partial combustion includes regulating the ratio of the contents of the oxidizing agent and fuel, carried out by partial combustion, contributing to the production of an intermediate product of combustion - carbon monoxide. 17. The device according to 13, in which the regulation of partial combustion includes regulating the ratio of the contents of the oxidizing agent and fuel, carried out by partial combustion, contributing to the production of an intermediate product of combustion - carbon monoxide. 18. The device according to any one of claims 1 to 10, in which air is used as an oxidizing agent. 19. The device according to claim 11, in which air is used as an oxidizing agent. 20. The device according to any one of claims 1 to 10, in which the gaseous fuel is fuel for a gas turbine engine or fuel for a reciprocating internal combustion engine and / or includes methane. 21. The device according to any one of claims 1 to 7, in which the gaseous fuel is a fuel for a gas turbine engine or fuel for a reciprocating internal combustion engine and / or includes methane. 22. A gas turbine engine containing a device in accordance with any one of claims 1 to 21, installed in its pipeline for supplying fuel. 23. A method of modifying the composition of a gaseous fuel, comprising the steps of using an oxidizing agent to partially burn the first part of the gaseous fuel to produce partial combustion products, including intermediate combustion products, and mixing the partial combustion products with the rest of the fuel, not partially burned, thereby obtaining a modified fuel while partial combustion is controlled so as to provide intermediate combustion products necessary for production va predetermined modified fuel.

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